Shielding for multicore shielded wire

ABSTRACT

A plurality of shielded core wires has a first diameter. A conductive cover member covers the shielded core wires. A first insulating sheath covers the conductive cover member. A pair of resin members, each formed with a groove having a semi-ellipsoidal shape are thermally integrated with each other for forming an ellipsoidal through hole while accommodating the first insulating sheath therein. A major axis length of a cross section of the ellipsoidal through hole is substantially identical with a length obtained by adding each first diameter, twice a thickness of the conductive cover member and twice a thickness of the first insulating sheath. A minor axis length of a cross section of the ellipsoidal through hole is substantially identical with by adding the first diameter, twice the thickness of the conductive cover member and twice the thickness of the first insulating sheath.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to the shielding method andstructure for a multicore shielded wire for electrically connecting ashielding cover of the multicore shielded wire and a grounding wire.

[0002] A related shield processing structure is disclosed in JapanesePatent Publication No. 11-135167A as shown in FIGS. 8 and 9.

[0003] In the branching structure shown in these figure, a braided wire120 d of a shielded wire 120 is electrically connected to a conductivewire 123 a of a grounding wire 123 by an ultrasonic horn 125 through apair of resin members 121 and 122.

[0004] In other words, the shielded wire 120 is constituted by oneshielding core 120 c having a core 120 a covered with an insulatinginner sheath 120 b, a conductive braided wire 120 d for covering theouter periphery of the shielding core 120 c, and an insulating outersheath 120 e for further covering the outer periphery of the braidedwire 120 d. A pair of resin members 121 and 122 have concave portions121 b and 122 b for forming a hole corresponding to the outer sectionalshape of the shielded wire 120 with mutual bonding faces 121 a and 122 abutted against each other, respectively. The grounding wire 123 isconstituted by the conductive wire 123 a and an insulating outer sheath123 b for covering an outer periphery thereof. The ultrasonic horn 125is constituted by a lower support base (not shown) provided in a lowerpart and an ultrasonic horn body 125 a provided in an upper part.

[0005] Next, a blanching procedure will be described. The lower resinmember 122 is provided on the lower support base (not shown) of theultrasonic horn 125, the shielded wire 120 is mounted from thereabove,one end of the grounding wire 123 is mounted thereon, and furthermore,the upper resin member 121 is put from thereabove. Thus, the shieldedwire 120 is provided in the concave portions 121 b and 122 b of theresin members 121 and 122, and the grounding wire 123 is providedbetween the shielded wire 120 and the upper resin member 121.

[0006] In this state, a vibration is applied by the ultrasonic horn 125while applying compression force between the resin members 121 and 122.Consequently, the insulating outer sheath 120 e of the shielded wire 120and the insulating outer sheath 123 b of the grounding wire 123 arefused and scattered by the internal heat generation of a vibrationenergy so that the conductive wire 123 a of the grounding wire 123 andthe braided wire 120 d of the shielded wire 120 come in electricalcontact with each other. Moreover, each of the contact portions of thebonding faces 121 a and 122 a of the resin members 121 and 122, thecontact portion of the internal peripheral faces of the concave portions121 b and 122 b of the resin members 121 and 122, the insulating outersheath 120 e of the shielded wire 120, the contact portion of theinsulating resin 123 b of the grounding wire 123, and the resin members121 and 122 are fused by the heat generation of the vibration energy andthe fused portions are solidified after the ultrasonic vibration iscompletely applied. Consequently, the resin members 121 and 122, theshielded wire 120 and the grounding wire 123 are fixed to each other.

[0007] According to the branch processing, it is not necessary to peelthe insulating outer sheaths 120 e and 123 b of the shielded wire 120and the grounding wire 123, and the lower resin member 122, the shieldedwire 120, the grounding wire 123 and the upper resin member 121 aresimply assembled in this order to give the ultrasonic vibration.Consequently, the number of steps is decreased, and a complicated manualwork is not required and automation can also be achieved.

[0008] In the branching structure, the single core type shielded wire120 can be properly shielded. However, if the same structure is appliedto a multicore type shielded wire having a different internalconfiguration, the following drawbacks would be occurred.

[0009] More specifically, a multicore shielded wire has such a structurethat a plurality of shielded core wires are accommodated with aclearance in the internal space of an insulating outer sheath and abraided wire. For this reason, the degree of a close contact and thearrangement relationship between the braided wire and the shielded corewires are indefinite with an interposition between the resin members 121and 122. In some cases in which the degree of a close contact isexcessive, the insulating inner sheath of the shielded core wire isbroken or cut upon receipt of the transmission of great vibrationenergy. Consequently, the grounding wire or the shielding cover comes incontact with the core to cause a short circuit, and furthermore, thestrength of the multicore shielded wire is reduced.

[0010] In order to eliminate such a drawback, it can be proposed thatthe vibration energy to be applied by the ultrasonic vibration Isreduced. However, in such a condition, a bonding strength based on thefusion and solidification between the resin members 121 and 122 isaccordingly reduced.

SUMMARY OF THE INVENTION

[0011] It is therefore an object of the invention to provide a structureand a method for shielding a multicore shielded wire in which a shortcircuit can be prevented from being caused by the contact of a groundingwire or a shielding cover with a core wire so that the strength of themulticore shielded wire can be prevented from being reduced.

[0012] In order to achieve the above object, according to the presentinvention, there is provided a multicore shielded wire, comprising:

[0013] a plurality of shielded core wires, each having a first diameter;

[0014] a conductive cover member, which covers the shielded core wires;

[0015] a first insulating sheath, which covers the conductive covermember; and

[0016] a pair of resin members, each formed with a groove having asemi-ellipsoidal shape and thermally integrated with each other forforming an ellipsoidal through hole while accommodating the firstinsulating sheath therein,

[0017] wherein a major axis length of a cross section of the ellipsoidalthrough hole is substantially identical with a length obtained by addingeach first diameter, twice a thickness of the conductive cover memberand twice a thickness of the first insulating sheath; and

[0018] wherein a minor axis length of a cross section of the ellipsoidalthrough hole is substantially identical with by adding the firstdiameter, twice the thickness of the conductive cover member and twicethe thickness of the first insulating sheath.

[0019] Preferably, the multicore shielded wire further comprises abranch wire, in which a conductive core wire is covered with a secondinsulating sheath, the branch wire sandwiched between the firstinsulating sheath and one of the resin members. A part of the firstinsulating sheath and a part of the second insulating sheath arethermally fused so that the conductive cover member and the conductivecore wire are electrically connected.

[0020] In order to attain the same advantages, according to the presentinvention, there is also provided a multicore shielded wire, comprising:

[0021] a plurality of shielded core wires, each having a first diameter;

[0022] at least one drain wire, having a second diameter which issmaller than the first diameter;

[0023] a conductive cover member, which covers the shielded core wiresand the drain wire;

[0024] a first insulating sheath, which covers the conductive covermember, and

[0025] a pair of resin members, each formed with a groove having asemi-ellipsoidal shape and thermally integrated with each other forforming an ellipsoidal through hole while accommodating the firstinsulating sheath therein,

[0026] wherein a major axis length of a cross section of the ellipsoidalthrough hole is substantially identical with a length obtained by addingeach first diameter, the second diameter, twice a thickness of theconductive cover member and twice a thickness of the first insulatingsheath; and

[0027] wherein a minor axis length of a cross section of the ellipsoidalthrough hole is substantially identical with by adding the firstdiameter, twice the thickness of the conductive cover member and twicethe thickness of the first insulating sheath.

[0028] Preferably, the multicore shielded wire further comprises abranch wire, in which a conductive core wire is covered with a secondinsulating sheath, the branch wire sandwiched between the firstinsulating sheath and one of the resin members. A part of the firstinsulating sheath and a part of the second insulating sheath arethermally fused so that the conductive cover member and the conductivecore wire are electrically connected.

[0029] In order to attain the same advantages, according to the presentinvention, there is also provided a method of shielding a multicoreshielded wire, comprising the steps of:

[0030] providing a plurality of shielded core wires, each having a firstdiameter;

[0031] covering the shielded core wires with a conductive cover member;

[0032] covering the conductive cover member with a first insulatingsheath

[0033] providing a branch wire, in which a conductive core wire iscovered with a second insulating sheath;

[0034] pressurizing the first insulating sheath so as to have anellipsoidal cross section in which the shielded core wires are alignedin a major axis direction of the ellipsoidal cross section;

[0035] providing a pair of resin members, each formed with a groovehaving a semi-ellipsoidal shape;

[0036] sandwiching the first insulating sheath and the branch wirebetween the resin members, such that the first insulating sheath isaccommodated within an ellipsoidal through hole formed by the groovesand such that the branch wire is placed between the first insulatingsheath and one of the resin members;

[0037] applying a ultrasonic vibration such that the resin members areintegrated with each other, while thermally fusing a part of the firstinsulating sheath and a part of the second insulating sheath so that theconductive cover member and the conductive core wire are electricallyconnected,

[0038] wherein a major axis length of a cross section of the ellipsoidalthrough hole after the ultrasonic vibration applying step issubstantially identical %With a length obtained by adding each firstdiameter, twice a thickness of the conductive cover member and twice athickness of the first insulating sheath; and

[0039] wherein a minor axis length of a cross section of the ellipsoidalthrough hole after the ultrasonic vibration applying step issubstantially identical with by adding the first diameter, twice thethickness of the conductive cover member and twice the thickness of thefirst insulating sheath.

[0040] In order to attain the same advantages, according to the presentinvention, there is also provided a method of shielding a multicoreshielded wire, comprising the steps of:

[0041] providing a plurality of shielded core wires, each having a firstdiameter;

[0042] providing at least one drain wire, having a second diameter whichis smaller than the first diameter;

[0043] covering the shielded core wires and the drain wire with aconductive cover member;

[0044] covering the conductive cover member with a first insulatingsheath;

[0045] providing a branch wire, in which a conductive core wire iscovered with a second insulating sheath;

[0046] pressurizing the first insulating sheath so as to have anellipsoidal cross section in which the shielded core wires and the drainwire are aligned in a major axis direction of the ellipsoidal crosssection;

[0047] providing a pair of resin members, each formed with a groovehaving a semi-ellipsoidal shape;

[0048] sandwiching the first insulating sheath and the branch wirebetween the resin members, such that the first insulating sheath isaccommodated within an ellipsoidal through hole formed by the grooveesand such that the branch wire is placed between the first insulatingsheath and one of the resin members;

[0049] applying a ultrasonic vibration such that the resin members areintegrated with each other, while thermally fusing a part of the firstinsulating sheath and a part of the second insulating sheath so that theconductive cover member and the conductive core wire are electricallyconnected,

[0050] wherein a major axis length of a cross section of the ellipsoidalthrough hole after the ultrasonic vibration applying step issubstantially identical with a length obtained by adding each firstdiameter, each second diameter, twice a thickness of the conductivecover member and twice a thickness of the first insulating sheath; and

[0051] wherein a minor axis length of a cross section of the ellipsoidalthrough hole after the ultrasonic vibration applying step issubstantially identical with by adding the first diameter, twice thethickness of the conductive cover member and twice the thickness of thefirst insulating sheath.

[0052] In the above configurations, the conductive cover member deformsscarcely even if the pressing force is applied to the multicore shieldedwire at the time of sandwiching the multicore shielded wire between thepair of the resin members, the branch wire and the conductive covermember before the fusing process caused by the ultrasonic vibration aredisposed at the constant positions, and the plurality of the shieldedcore wires can scarcely move. Thus, the shielded core wires are notdisplaced even when the pressure and the ultrasonic vibration isapplied. Thus, the insulating sheath of the shielded core wires are notbroken or out due to the heat generated by the ultrasonic vibration.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The above objects and advantages of the present invention willbecome more apparent by describing in detail preferred exemplaryembodiments thereof with reference to the accompanying drawings,wherein:

[0054]FIG. 1 is a sectional view of a multicore shielded wire accordingto an embodiment of the invention;

[0055]FIG. 2 is a diagram showing a shape forming processing for themulticore shielded wire;

[0056]FIG. 3 is a sectional diagram of the multicore shielded wirehaving been subjected to the shape forming processing;

[0057]FIG. 4 is a perspective view of a pair of resin members used forthe multicore shielded wire;

[0058]FIG. 5 is a diagram showing a setting state of respective membersbefore applying ultrasonic vibration thereto;

[0059]FIG. 6 is a diagram showing the shielding structure obtained bythe application of the ultrasonic vibration;

[0060]FIG. 7 is a perspective view of the multicore shielded wireobtained by the shielding of the invention;

[0061]FIG. 8 Is a front view showing a shielding structure according toa related art; and

[0062]FIG. 9 is a sectional view showing the shielding structureaccording to the third related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] Hereinafter, the preferred embodiments of the invention will beexplained with reference to the accompanying drawings.

[0064]FIG. 1 shows a multicore shielded wire according to one embodimentof the invention. The multicore shielded wire 1 is constituted by twoshielded core wires 4 each having a core wire 2 covered with aninsulating inner sheath 3, a drain wire 5, an aluminum foil to be ashielding cover 6 for covering the outer periphery of the two shieldedcore wires 4 and the drain wire 5, and an insulating outer sheath 7 forfurther covering the outer periphery of the shielding cover 6. Theinsulating inner sheath 3 and the insulating outer sheath 7 are formedof a synthetic resin, and the core wire 2 and the drain wire 5 areformed of a conductive material.

[0065] As shown in FIG. 2, the multicore shielded wire 1 having thealmost circular shape In its outer sectional configuration is deformedin its shape by a pair of upper and lower deformation jigs 8, 9 made ofresin and having shallow recess portions 8 a, 9 a on their opposingsides thereof, respectively. That is, the multicore shielded wire 1 isdisposed between the pair of upper and lower deformation jigs 8, 9 andis compressed in the elevational direction by the jigs 8, 9. Thus, themulticore shielded wire 1 is deformed while being restricted by therecess portions 8 a, 9 a. Then, as shown in FIG. 3, the multicoreshielded wire 1 is deformed in a manner that the two shielded core wires4 and the drain wire 5 are laterally aligned in a line so as to have analmost elliptical shape in the outer sectional configuration of themulticore shielded wire. In this respect, although in FIG. 3 the twoshielded core wires 4 and the drain wire 5 are disposed in the order ofthe shielded core wire 4, the shielded core wire 4 and the drain wire 5from the left side, these wires may be disposed in any order so long asthe two shielded core wires 4 and the drain wire 5 are laterally alignedin a line.

[0066] As shown In FIG. 4, a pair of resin members 10 and 11 are blockshaving the same shape and formed of a synthetic resin, and concaveportions 10 b and 11 b for forming a hole almost corresponding to theouter sectional shape of the shielded wire 1 are formed with mutualbonding faces 10 a and 11 a abutted against each other, respectively. Indetail, each of the recess portions 10 b, 11 b is a groove of an almostsemi-elliptical shape formed by dividing the elliptical shape of themulticore shielded wire 1.

[0067] As shown in FIG. 6, the hole of the almost elliptical shapeformed by abutting the surfaces 10 a, 11 a to each other is set in amanner that a length a in the minor axis direction thereof is sum of theouter diameter of the shielded core wire 4 and twice the thickness ofthe shielding cover 6 and the insulating outer sheath 7. Further, thehole is set in a manner that a length b in the major axis directionthereof is sum of twice the outer diameter of the shielded core wire 4,the outer diameter of the drain wire 5 and twice the thickness of theshielding cover 6 and the insulating outer sheath 7.

[0068] As the physical properties of the resin members 10 and 11,moreover, they are less fused than the insulating outer sheath 7 and areformed of an acryl based resin, an ABS (acrylonitrile-butadiene-styrenecopolymer) based resin, a PC (polycarbonate) based resin, a PE(polyethylene) based resin, a PEI (polyetherimide) based resin or a PBT(polybutylene terephthalate) based resin, and are generally harder thanvinyl chloride to be used for the insulating outer sheath 7.

[0069] In respect of conductivity and conductive safety, practicality isrequired for all the resins described above and the PEI (polyetherimide)based resin and the PBT (polybutylene terephthalate) based resin areparticularly suitable if a decision is carried out including appearanceand insulating properties.

[0070] As shown in FIG. 5, the grounding wire 13 Is configured by aconductive wire 13 a and an insulating outer sheath 13 b covering theouter periphery thereof.

[0071] As shown in FIG. 5, an ultrasonic horn 15 is configured by alower support base 15 a capable of positioning the resin member 11disposed beneath and an ultrasonic horn body 15 b disposed just abovethe lower support base 15 a and capable of applying ultrasonic vibrationwhile acting pressing force beneath.

[0072] Next, the shielding procedure will be explained. First, the shapeforming processing is performed in which a portion in the vicinity ofthe end portion of the multicore shielded wire 1 having a circular shapein its outer sectional configuration is formed in an almost ellipticalshape in its outer sectional configuration by using the deformation jigs8, 9. According to the shape forming processing, as shown in FIG. 3, themulticore shielded wire 1 is deformed in a manner that the two shieldedcore wires 4 and the drain wire 5 are laterally aligned in a line so asto have an almost elliptical shape in the outer sectional configurationof the multicore shielded wire.

[0073] Next, as shown in FIG. 5, the resin member 11 on the lower sideis disposed on the lower support base 15 a of the ultrasonic horn 15,then the portion near the end portion of the multicore shielded wire 1having been subjected to the shape forming processing is disposed on theresin member, then the one end side of the grounding wire 13 is disposedon the multicore shielded wire, and the resin 10 on the upper side iscovered over the muIlticore shielded wire and the grounding wire. Inthis manner, the multicore shielded wire 1 is disposed within the recessportions 10 b, 11 b of the pair of the resin members 10, 11, and the oneend of the grounding wire 13 is disposed between the multicore shieldedwire 1 and the upper resin member 11.

[0074] Next, the ultrasonic horn body 15 b is brought down to give avibration through the ultrasonic horn 15 while applying the compressionforce between the resin members 10 and 11. Consequently, the insulatingouter sheath 7 of the shielded wire 1 and the insulating outer sheath 13b of the grounding wire 13 are fused and scattered by the internal heatgeneration of a vibration energy so that the conductive wire 13 a of thegrounding wire 13 and the aluminum foil 6 a of the shielded wire 1 comein electric contact with each other (see FIG. 6).

[0075] Moreover, each of the contact portions of the bonding faces 10 aand 11 a of the resin members 10 and 11, the contact portion of theinternal peripheral faces of the concave portions 10 b and 11 b of theresin members 10 and 11 and the insulating outer sheath 7 of theshielded wire 1, and the contact portion of the insulating resin 13 b ofthe grounding wire 13 and the resin members 10 and 11 are fused by theinternal heat generation of the vibration energy and the fused portionsare solidified after the ultrasonic vibration is completely applied.Consequently, the resin members 10 and 11, the shielded wire 1 and thegrounding wire 13 are fixed to each other (see FIGS. 6 and 7).

[0076] Consequently, it is not necessary to peel the insulating outersheaths 7 and 13 b of the shielded wire 1 and the grounding wire 13 andit is preferable that the lower resin member 11, the shielded wire 1,the grounding wire 13 and the upper resin member 10 should be assembledin this order to give the ultrasonic vibration. Therefore, the number ofsteps is decreased, and a complicated manual work is not required andautomation can also be achieved.

[0077] In the aforesaid processing, in the multicore shielded wire 1,the plurality of the shielded core wires 4 scarcely move due to theholding force between the pair of the resin members 10, 11. Further, themulticore shielded wire is deformed in such an outer configuration thatthe shielding cover 6 scarcely deforms. Thus, the shielding cover 6 alsoscarcely deforms (moves) due to the pressing force generated when themulticore shielded wire 1 is sandwiched between the pair of the resinmembers 10, 11, and the grounding wire 13 and the shielding cover 6before the fusing process caused by the ultrasonic vibration aredisposed at the constant positions. Therefore, the grounding wire 13 andthe shielding cover 6 can be surely made in contact electrically to eachother due to the fusing process and so the electric efficiency can beimproved.

[0078] Further, since the two shielded core wires 4 can scarcely move,the two shielded core wires do not vary in their positions even when thepressure and the ultrasonic vibration is applied between the pair of theresin members 10, 11 at the time of the fusing process. Thus, theinsulation inner covers 3 of the shielded core wires 4 are not broken orcut due to the heat generated by the ultrasonic vibration, and so theoccurrence of the short-circuit between the grounding wire 13 and thecore wire 2 and between the core wires 2 can be surely prevented and theinsulation efficiency can be improved.

[0079] In the aforesaid embodiment, since the shape forming processingof the multicore shielded wire 1 is performed in a manner that themulticore shielded wire is deformed by the compression force appliedfrom the outside to have an almost elliptical shape in its outersectional configuration so that the two shielded core wires 4 arelaterally aligned in a line. Thus, it is merely required to apply thecompression force to the multicore shielded wire 1 from the elevationaldirection, for example, such a forming processing can be conductedeasily.

[0080] In the above embodiment, when a plated wire having a relativelylow melting temperature such as a tin plated electric wire is used asthe conductive wire 13 a of the grounding wire 13, the plated wire ispartially fused by a vibration energy and better electric contact withthe shielding cover 6 can be obtained. Therefore, a reliability in thecontact portion of the shielding cover 6 and the conductive wire 13 a ofthe grounding wire 13 can be enhanced. The relatively low meltingtemperature can be defined as a temperature which is lower than atemperature of the internal heat generated by the ultrasonic vibration.

[0081] In the above embodiment, the sizes a and b of the hole formed bythe recess portions 10 b, 11 b of the resin members 10, 11 are set tohave such values capable of housing the multicore shielded wire 1without leaving any clearance. Thus, since the members of the multicoreshielded wire 1 can scarcely move on or after the fusing process causedby the ultrasonic vibration, a very rigid shielding structure can beobtained. In this respect, even if the sizes a and b of the hole formedby the resin members 10, 11 are set to have such values that the holehas a clearance slightly with respect to the outer configuration size ofthe multicore shielded wire 1, the similar effects can be obtained.

[0082] While the insulating outer sheath 13 b is not peeled when thegrounding wire 13 is arranged between the resin member and the shieldedwire in the above embodiments, the insulating outer sheath 13 b may bepeeled. Furthermore, the contact connection of the shielding cover 6 andthe conductive wire 13 a is not restricted to thermal fusing based on anultrasonic vibration.

[0083] While the aluminum foil 6 a is used for the shielding cover 6 inthe above embodiments, a conductive metal other than aluminum,particularly, a material having an excellent rolling property can alsobe used. Alternatively, a braided wire may be adopted as the shieldingcover 6.

[0084] While the multicore shielded wire is provided with the drain wire5 in the above embodiments, the drain wire 5 does not need to be alwaysprovided. If the drain wire 5 is provided, the shielding can also becarried out by earthing the drain wire 5. Therefore, there is anadvantage that a variation in a countermeasure against the shielding canbe increased correspondingly.

[0085] Although in the above embodiment, the explanation has been madeas to the case where the multicore shielded wire 1 has the two shieldedcare wires 4, it goes without saying that the invention is also appliedto the case where the multicore shielded wire has three or more shieldedcore wires 4.

What is claimed is:
 1. A multicore shielded wire, comprising: aplurality of shielded core wires, each having a first diameter; aconductive cover member, which covers the shielded core wires; a firstinsulating sheath, which covers the conductive cover member; and a pairof resin members, each formed with a groove having a semi-ellipsoidalshape and thermally integrated with each other for forming anellipsoidal through hole while accommodating the first insulating sheaththerein, wherein a major axis length of a cross section of theellipsoidal through hole is substantially identical with a lengthobtained by adding each first diameter, twice a thickness of theconductive cover member and twice a thickness of the first insulatingsheath; and wherein a minor axis length of a cross section of theellipsoidal through hole Is substantially Identical with by adding thefirst diameter, twice the thickness of the conductive cover member andtwice the thickness of the first insulating sheath.
 2. The multicoreshielded wire as set forth in claim 1, further comprising a branch wire,in which a conductive core wire is covered with a second insulatingsheath, the branch wire sandwiched between the first insulating sheathand one of the resin members, wherein a part of the first insulatingsheath and a part of the second insulating sheath are thermally fused sothat the conductive cover member and the conductive core wire areelectrically connected.
 3. A multicore shielded wire, comprising: aplurality of shielded core wires, each having a first diameter; at leastone drain wire, having a second diameter which is smaller than the firstdiameter; a conductive cover member, which covers the shielded corewires and the drain wire; a first insulating sheath, which covers theconductive cover member; and a pair of resin members, each formed with agroove having a semi-ellipsoidal shape and thermally integrated witheach other for forming an ellipsoidal through hole while accommodatingthe first insulating sheath therein, wherein a major axis length of across section of the ellipsoidal through hole is substantially identicalwith a length obtained by adding each first diameter, the seconddiameter, twice a thickness of the conductive cover member and twice athickness of the first insulating sheath; and wherein a minor axislength of a cross section of the ellipsoidal through hole issubstantially identical with by adding the first diameter, twice thethickness of the conductive cover member and twice the thickness of thefirst insulating sheath.
 4. The multicore shielded wire as set forth inclaim 1, further comprising a branch wire, in which a conductive corewire is covered with a second insulating sheath, the branch wiresandwiched between the first insulating sheath and one of the resinmembers, wherein a part of the first insulating sheath and a part of thesecond insulating sheath are thermally fused so that the conductivecover member and the conductive core wire are electrically connected. 5.A method of shielding a multicore shielded wire, comprising the stepsof: providing a plurality of shielded core wires, each having a firstdiameter; covering the shielded core wires with a conductive covermember; covering the conductive cover member with a first insulatingsheath; providing a branch wire, in which a conductive core wire iscovered with a second insulating sheath; pressurizing the firstinsulating sheath so as to have an ellipsoidal cross section in whichthe shielded core wires are aligned in a major axis direction of theellipsoidal cross section; providing a pair of resin members, eachformed with a groove having a semi-ellipsoidal shape; sandwiching thefirst insulating sheath and the branch wire between the resin members,such that the first insulating sheath is accommodated within anellipsoidal through hole formed by the groovees and such that the branchwire is placed between the first insulating sheath and one of the resinmembers; applying a ultrasonic vibration such that the resin members areintegrated with each other, while thermally fusing a part of the firstinsulating sheath and a part of the second insulating sheath so that theconductive cover member and the conductive core wire are electricallyconnected, wherein a major axis length of a cross section of theellipsoidal through hole after the ultrasonic vibration applying step issubstantially identical with a length obtained by adding each firstdiameter, twice a thickness of the conductive cover member and twice athickness of the first insulating sheath; and wherein a minor axislength of a cross section of the ellipsoidal through hole after theultrasonic vibration applying step is substantially identical with byadding the first diameter, twice the thickness of the conductive covermember and twice the thickness of the first insulating sheath.
 6. Amethod of shielding a multicore shielded wire, comprising the steps of:providing a plurality of shielded core wires, each having a firstdiameter; providing at least one drain wire, having a second diameterwhich is smaller than the first diameter; covering the shielded corewires and the drain wire with a conductive cover member; covering theconductive cover member with a first insulating sheath; providing abranch wire, in which a conductive core wire is covered with a secondinsulating sheath; pressurizing the first insulating sheath so as tohave an ellipsoidal cross section in which the shielded core wires andthe drain wire are aligned in a major axis direction of the ellipsoidalcross section; providing a pair of resin members, each formed with agroove having a semi-ellipsoidal shape; sandwiching the first insulatingsheath and the branch wire between the resin members, such that thefirst insulating sheath is accommodated within an ellipsoidal throughhole formed by the groovees and such that the branch wire is placedbetween the first insulating sheath and one of the resin members;applying a ultrasonic vibration such that the resin members areintegrated with each other, while thermally fusing a part of the firstinsulating sheath and a part of the second insulating sheath so that theconductive cover member and the conductive core wire are electricallyconnected, wherein a major axis length of a cross section of theellipsoidal through hole after the ultrasonic vibration applying step issubstantially identical with a length obtained by adding each firstdiameter, each second diameter, twice a thickness of the conductivecover member and twice a thickness of the first insulating sheath; andwherein a minor axis length of a cross section of the ellipsoidalthrough hole after the ultrasonic vibration applying step issubstantially identical with by adding the first diameter, twice thethickness of the conductive cover member and twice the thickness of thefirst insulating sheath.